Family Description:
Species in this family reportedly have a life cycle like the Acrosiphoniaceae, with a filamentous gametophyte and a unicellular sporophyte. The gametophytes have mostly unbranched filaments. The filaments are composed of cylindrical cells lined up end to end. Each cell is separated from its neighbors by distinct cell walls and contains a single nucleus and a single chloroplast. The chloroplast characteristically is collar-shaped, forming a band around the periphery of the cell, and usually has a single pyrenoid.

Species description:
Mermaid's Tresses form bright green strands that carpet or hang in long, straight strings from intertidal rocks. These strings, or filaments, are 20 to 40 micrometers in diameter. Since they are unbranched, when you pull them gently they separate easily (unlike the much shorter-stranded Acrosiphonia).

We have seen this species commonly in Southeast Alaska in spring. At Glacier Bay it is reported to occur to within about 400 meters (1/4 mile) of the face of glaciers.

Source:  North Pacific Seaweeds